[gnome-shell] main: Show a warning when gdm is missing

[Florian Müllner <fmuellner src gnome org>]

commit 7326e7a9fad0e82e137680ebcb0cdec81813003c
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Jun 8 13:33:58 2013 -0400

    main: Show a warning when gdm is missing
    
    If we are not running under gdm, some functionaliy (such as
    the lock screen) does not work, and we should inform the
    user about this.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=701212

 js/ui/main.js | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/js/ui/main.js b/js/ui/main.js
index d8b0b9b6a4..ab5aff0dcb 100644
--- a/js/ui/main.js
+++ b/js/ui/main.js
@@ -268,6 +268,13 @@ function _initializeUI() {
                    _('Running a session as a privileged user should be avoided for security reasons. If 
possible, you should log in as a normal user.'));
         }
 
+        if (sessionMode.currentMode !== 'gdm' &&
+            sessionMode.currentMode !== 'initial-setup' &&
+            screenShield === null) {
+            notify(_('Screen Lock disabled'),
+                   _('Screen Locking requires the GNOME display manager.'));
+        }
+
         LoginManager.registerSessionWithGDM();
 
         let perfModuleName = GLib.getenv("SHELL_PERF_MODULE");